Roofing installation and method of forming the same



June 26, 1945. F. B. WALLACE 2,379,051

ROOFING INSTALLATION AND METHOD OF FORMING THE SAME Filed Dec. 7, 1945 2 Sheets-Sheet 1 June 26, 1945. F, B.-WALLAC E 2,379,051

ROOFING INSTALLATION AND METHOIS OF FORMING THE SAME Filed Dec. 7, 1943 2 SheetsrSheet 2 Patented June 26, 1945 ROOFING INSTALLATION AND METHOD OF FORMING THE SAME Frank B. Wallace, Silver Spring, Md.

Application December 7, 1943, 'Seiial No. 513,286

'6 Claims.

My invention relates generally to a roof installation embodying an exterior shingle simulating surface composed of a self-hardening plastic composition, and is an improvement on the roof installation as disclosed in my Patent No. 2,198,- 685 issued to me on'Aprii 30, 1940.

In its more specific aspects my invention provides an exterior water run off roof surface composed of a self-hardening plastic composition, such as cement or the like, which is poured, struck off, and allowed to harden in place on the roof supporting structure; while the exterior of the plastic surface of my invention is treated to simulate a shingle roof, there is no overlapping of shingles as in the customary roof, and the plastic surface provides a. plurality of one piece unitary slab sections for each roof section as opposed to exterior root surfaces composed of a plurality of individual overlapping, wood, composition or the like, shingles. Such plastic roof structures are highly desirable, but in practice present certain problems which are not encountered in usual roofs composed of a plurality of individual wood, composition or the likeshingles. I have successfully solved the difliculties which have arisen in the use of such self-hardening plastic composition roofs in a manner as hereinafter described.

In maznyrooi installations a supporting surface is provided by laying wood sheathing on the roof rafters, and I :propose 'to cover such sheathing with a waterproof shecting'p ior to laying-thereon the upper cement or the like shingle simulating surface. have found that a flexible felt material having a coal tar covering may be successfully used fol-this purpose, although there are a number of other waterproof coverings which may be used with equally good results. The waterproof covering orsheeting which is applied to the roof sheathing is customarily supplied to the user in rolls, and is laid on and applied to the sheathing in sheets with the edges of adiacent sheets disposed in lapped relation. A metallic mesh reinforcement is laid on the sheeting and fastened thereto in a particular manner to provide an anchor or bonding medium for theplastic'exterior surface whichis laid thereon. Instead of using a metallic mesh reinforcement as an anchor, the sheeting may be treated just prior to pouring the plastic with an asphalt paint which provides an anchor therefore, or a slate surfaced roll sheeting may be used for this purpose with excellent results.

As exterior shingle simulating plastic roofsurface'is iprimarilydesignedto keep the sun oil the waterproof felt or the like covering upon which the plastic is laid to thereby substantially prolong the useful life of such covering, and is not intended to be completely waterproof. Due to weight and economy factors, it is desirable that the plastic roof surface be relatively thin, which construction, along with expansion and contraction of the plastic slabs, often results in the development of cracks therein and consequent leakage of 'water and moisture through the plastic to the under Waterproof covering of felt or'the like material.

Water which may leak onto the waterproof covering through cracks which have developed in the plastic slabs causes a backing up or water, or the generation of water pressure between the plas tic surface and the waterproof covering. Such water will leak through any imperfections which may exist at the seal between the lap joints of the waterproof covering or sheets, or which may exist at any other points on the covering, and a leaking im erfect and unsatisfactory roof will result.

I have devised a roof structure, having'an upper water run-off surface composed'of plastic material, and a method of forming such roof structure, whereby water, which may leak through cracks or imperfections in the plastic surrace'wlll not accumulate between the plastic surface and the waterproof covering but instead will b freely drained therefrom to the exterior of the plastic surface to run its normal course from the roof. I have accomplished this highly advantageous and "desirable result without sacrificing speed or econonly of installation or any artistic or decorative characteristic of roofs.

My roof structure has also been designed to eliminate or substantially reduce the tendency of plastic roofs to crack due to expansion and contraction of the plastic. This has been accomplished by providing a novel and highly satisfactory association of roof forming independent plastic slabs, which permits of norm-a1 expansion and contraction of the plastic without causing cracking thereof.

As the description of my invention proceeds, it will become apparent that the-invention may be applied to a wall as well as to a roof, and that the roofing installation and the method of application may also be followed in valleys and roof jacks without departing. from the spirit and scope of my invention.

It-is, therefore, a fundamental object of my invention to provide a roofing installation having an exterior water run-oil surface composed of a plastic material which installation eliminates the accumulation of water between said exterior surface and the next adjacent under surface on which the plastic is laid.

A further and equally important object of my invention is to provide a roofing installation having a system of water drainage for facilitating the removal of water from between the exterior roof surface and the next adjacent under surface.

Another object of my invention is to so combine and associate the exterior plastic roof surface of a roofing installation with the next adjacent under surface that any water or moisture which might penetrate the plastic surface will not remain on the next adjacent under surface but will be freely drained therefrom.

Another object of my invention is to provide a roofing installation in which the exterior water run-off surface is composed of a plastic material treated to simulate shingles and which roofing installation will not leak in the event cracks develop in such plastic surface.

A further object of my invention is to provide a roofing installation in which the exterior plastic surface is so laid and associated in independent slab like form that the tendency to crack under expansion and contraction of the plastic will be substantially reduced.

Another object of my invention is to provide a durable and attractive roof edge structure.

It is also an object of my invention to provide a roofing installation having a plastic exterior water run-off surface which surface is poured, struck off or otherwise placed and allowed to harden in place on the roofing job.

Another object of my invention is to provide a roofing installation having an exterior water run-off surface which is composed of a plurality of separate slabs of plastic material.

It is also an object of my invention to provide a roofing installation having an exterior Water run-off surface which is composed of a plurality of separate slabs of plastic material, each slab comprising a series of individually laid courses of plastic material.

A further object of my invention is to provide a method of forming a roof of the character described.

And yet another object of my invention is to provide a roofing installation having an exterior shingle simulating water run-off surface composed of a plastic material which is economical to install and endowed with lasting qualities.

With the foregoing general objects, features and results in view, as well as certain others which will be apparent from the following explanation, the invention consists in certain novel features and designs. construction, mounting and combination of elements, as will be more fully and particularly referred to and specified hereinafter.

Referring to the accompanying drawings:

Fig. l is a perspective view of a portion of a roof constructed in accordance with this invention.

Fig, 2 is a view taken on line 2-2 of Fig. 1.

Fig. 3 is a perspective view of a roof, at one stage in the construction thereof, with parts broken away.

Fig. 4 is a perspective view of a roof, at one stage in a modified method of the construction thereof, with parts broken away.

Fig. 5 is a perspective view of a roof edge in the process of construction, with parts thereof broken away.

Fig. 6 is a perspective view of a roof edge with parts broken away.

Fig. 7 is a perspective view of a modified type of roof with parts thereof broken away.

Fig. 8 is a perspective view with parts thereof broken away, of the modified form of roof at one stage in the construction thereof.

Fig. 9 is a perspective view, with parts thereof broken away, of the modified form of roof at a more advanced stage in the construction thereof than that shown in Fig. 8.

In the form of my invention disclosed in Figs. 1, 2 and 3 of the drawings, I have used the numeral I to designate the customary wood sheathing which is laid on the rafters of a roof. Upon the sheathing I apply a waterproof covering or sheeting 3 which is laid in strips directly on such wood sheathing, it being understood that I start laying the strips of sheeting at the lower or eaves edge of the roof and work up to the ridge or top of the roof. The strips of sheeting are disposed on the sheathing in lapped relation to provide a substantial lapped joint I along the longitudinal edge portions thereof, each lapped joint comprising an upper lapped portion 8 and a lower lapped portion III. The upper lapped portion 8 being part of the strip of sheeting which is higher up the roof than that strip of which the lapped portion I0 is a part.

After the strips of sheeting 3 are laid on the sheathing I, wire mesh reinforcements 9 are laid on the strips of sheeting, each wire mesh reinforcement or chicken wire 9 being of substantially similar dimensions as the strips of sheeting, Each strip of sheeting and each strip of metallic mesh are fastened to the sheathing along and adjacent to the top or upper longitudinal edges of the strips only, by mean of roofing nails or the like 5, a blind nailing arrangement being had, as will be evident by referring particularly to Fig, 2 of the drawings. The mesh provides an anchor or bond for the exterior plastic surface which is laid directly thereon.

The sheathing I, sheeting 3 and metallic mesh 9 are adapted to receive and support an exterior shingle simulating water run-off surface I I composed of a plastic material, such as cement. As will be described, the plastic is laid in longitudinal courses and is preferably of a width and marked to present a surface having an appearance and decorative effect generally similar to that of the customary shingled roof. While I have described my roofing installation as being constructed to simulate a shingle roof, it is to be distinctly understood that any roof which is composed of a plastic and has the characteristics of my invention is intended to fall within the spirit and scope thereof.

The plastic exterior water run-off surface II is composed of a series of longitudinal shingle simulating courses A, B, C, D, E, F, G etc., each course having a lower thickened butt end I3 and an upper relatively thin end I5, and the exterior surface I I is marked in any convenient manner with grooves I1 to provide a shingle effect.

The advantageous and highly desirable results which I achieve require that the plastic material be laid on the sheeting and associated therewith in a particular manner. A roof section which has been prepared as described to receive the plastic exterior surface consists of sheathing covered with a plurality of lapped strips of waterproof sheeting, such as treated felt or the like on which is laid and secured a metallic mesh. Now such sheeting must be laid out and marked by the roof builder to indicate where thereon the courses of plastic are to be laid and the dimensions thereof. This must be done so that the workman laying the plastic courses will mold each course to proper dimensions in order that the series of courses will be laid with the required exactness relative to the lapped joints 1 of the waterproof covering. The sheeting or covering must be so marked for the laying of the plastic courses that the lower or butt ends 18 of certain courses of the series of courses lay in substantially the same vertical plane as the longitudinal edge of the upper lapped portion 8 of a strip of sheeting, see particularly Fig. 2 of the drawings.

As I have hereinbcfore stated, the plastic exterior water run-oil surface 11 is laid on the job, that is, the cement is laid, molded and hardens on the roof- I do not use ore-formed plastic shingles or the like.

Upon completion of the laying of the strips of waterproof sheeting and fastening the mesh thereto, the supporting structure is in readiness for receiving the plastic exterior surface. The plastic is laid in longitudinal courses starting at the top or ridge of the roof and working down the roof. Referring particularly to Fig. 1 of the drawings, the letter A designates the top course of plastic or cement which is laid first. After the course A is laid, the next adjacent lower'course B is laid, then course C, and so on until the roof section is covered by the plastic material. Before the plastic hardens, the grooves ll are formed therein.

In laying the shingle simulating plastic material in longitudinal courses as described above, a straight molding board or form 12 may be used, such board defining and molding the lower or butt end l3 .pf the course of plastic being laid, the thickness of the board preferably equalling the thickness of the lower end of the course. The workman laying the plastic spaces the board below the next adjacent upper course, which has been laid and molded, a distance equal to the desired width of the course, the upper longitudinal edge of the course being moldedor formed by the lower longitudinal or butt edge it of the next adjacent upper course. When the molding board is disposed in proper position and secured in place many convenient manner, the plastic material may be poured in the course defining area bounded by the molding board and the longitudinal or batteries: of the next adjacent upper course. The transverse course ends may be formed by short molding boards or in any other desirable or usual manner. When the plastic is poured, it is trowelled by the workmen to the desired slope and thickness at the upper end thereof, and then allowed to harden.

Each section of roof according to my invention, comprises a series of longitudinal courses A, B, C, D, etc., composed of plastic, and since the upper end 15 of a course is formed and laid against the lower or butt end l3 of the next adjacent upper course, adjacent courses will be bonded together to form slabs composed of a series "of courses of plastic. It may here be pointed out that in the specific example shown in the drawings each 'slab will be composed of four longitudinal courses, and each slab will be free and separate from the next adjacent slab. Therefore, each roof section-will be composed of a plurality of separate-subsections. The reasons and purpose oi -this construction will be explained hereinafter.

It be appreciated that theedges of adjacent courses are in "abutting relationship. and

hence, there is not the usual overlapping of the shingle like courses and the slabs are of single thickness.

In the specific construction shown in the drawings I have disclosed a strip of felt sheeting 3 as being of standard width which is generally sufficiently wide to accommodate four courses of plustic, in Fig. 1 of the drawings they are; C. D. E, F and also to accommodate the lapped portion 8 of the next adjacent upper strip of sheeting which is the equivalent of a part of course B. It will be obvious that the strips of sheetingmight be of any width; however, they must be of a width equal to more than the combined widths of a number of longitudinal courses.

As I have stated, it is essential in laying the plastic courses that they be so positioned and disposed that the vertical longitudinal edges of the butt ends IQ of every fourth course (in the specific embodiments shown in the drawings) be in the same vertical plane as that of the vertical longitudinal edges of the lapped portions 8 of each strip of sheeting 3.

In order to expose the longitudinal end of the lapped portion 8 of each strip of sheeting to the exterior or outer surface of the plastic surface .I I, I provide each fourth course C and G in a series of courses with a bevelled or gradually ,inclined upper surface l9, which is provided with a thin extending portion 20 which projects be tween a part of the lapped portions 8 and I8 and the plastic course F and terminates in a feather edge therebetween.

It will be appreciated that, as a result of this particular construction, the longitudinal lower edges of the sheets 3 will be exposed to the outer plastic surface H, each bevel I 8 forming a longitudinal drainage outlet for any water which might otherwise accumulate between the plastic and the sheets.

It will be appreciated that due to the bevelled structure of course G and the extending portion 20 thereof the edges of courses F and G will not abut and the two courses will not be bonded to gether. Thus an independent slab of plastic in the disclosed example will consist of courses C, D, E, F and the next lower slab will consist of those courses commencing with courses G and H and including two more courses (not shown).

The construction of each fourth course as described not only provides drainage outlets, but also provides a plastic roof of this type composed of a series of independent plastic slabs, each of which comprises a series of bonded shingle like courses. Furthermore, each plastic slab is supported on and bonded to a strip of sheeting and a strip of metallic mesh which are fastened at one edge only to the sheathing. Hence, each strip of mesh and each strip of sheeting which are secured together are independent relative to each of the remaining strips of mesh and strips of sheeting. Therefore, each plastic slab may expand and contract independently of every other plastic slab and. such expansion and contraction may effect a unit to which it is bonded or anchored without effectin any other bonding or anchoring unit of the roofing installation. Due to extension 20, sheeting ill will be covered under all conditions of expansion and contraction of the plastic slabs.

In Fig. 3 of the drawings I have shown a rapid and efficient method of florming the proper courses with the desired bevel and the extending portion.

When the workmanconstructing the roof has laidthe plastic forming course G, and before the plastic is allowed to harden, he takes his trowel 2|, projects it under the end I8 of course F and between the lapped portion 8 and ID of the strips of sheeting 3 and lifts the end of the still soft course F and lapped portion 8 up and runs his trowel the length of the course. In so doing the trowel is held and positioned substantially as shown in Fig. 2 of the drawingsto thereby form the slope l9 and force the plastic 9. distance under lapped portion 8 to form the extending plastic portion 20 terminating in a feather edge.

By means of the construction described, it will be apparent that any water or moisture which may leak through the plastic surface II will not back up or generate pressure between said surface and the sheeting 3, but instead will drain and freely run off the exposed end of the lapped portion 8 of each strip of sheeting 3 on to the outer roof surface. It will be appreciated that my construction provides a series of water drainage troughs spaced apart and disposed at the lower longitudinal edge of each strip of sheeting.

In a roofing installation of the construction described leaks will not develop even though the cement exterior surface cracks allowing water and moisture to penetrate such exterior roof surface. Any water or moisture which passes through the plastic surface will not accumulate on the felt sheeting seeking and discovering imperfections therein, instead such water and moisture, due to my novel construction, will readily drain from between the plastic surface and the sheeting. The drainage of water and moisture will occur at each fourth course where the longitudinal edges of the sheeting strips are exposed to the outer roof surface as a result of the bevelled structure of the next adjacent lower course of plastic. The method I have devised for constructing such a roof is simple and eminently productive of efficient results. Roofs of the type of this invention will not leak even though cracks develop in the plastic surface. This greatly desired drainage of water and moisture from the area between the exterior plastic surface and the waterproof sheathing is accomplished without increasing the difficulties or complexities of construction, and without necessitating the overlapping of the plastic shingle like course A, B, C, D, E, etc., as is customary in roof structures. The plastic exterior water run-off surface of my roofing installation is of single thickness, that is, there is no laying of plastic on plastic, and such surface presents roof of artistic stepped shingle-like appearance, without the undesirable necessity of an overlapping shingle or plastic course construction.

While in the specific example of my roofing installation which is shown in the drawings, I dispose a drainage point at each forth course, it is to be understood that it is my intention to dispose a drainage point at every course which is disposed on the lower longitudinal edge of each strip of sheeting.-

In Fig. 4 I disclose a modified method of pro= ducing drainage outlets at every fourth course. In this form of invention I provide a bevelled surface 22 which is formed by a straight molding .bar 2| of generally channel shape having a bevelled bottom portion 23 connecting the vertical portions of the bar, the longer vertical portion 25 constitutes a form for the butt end 13 of the next adjacent upper course to that course having the bevelled surface. The form or moldin bar 2| may be used in forming the bevel l9 instead of the hand trowel 2| described above. To form the grooves H in the plastic surface H I show a transverse bar 24 which may be mounted in any convenient manner on the members. l2 and 25. It will be appreciated that a plurality of such bars 24 will be used.

Instead of using the wire mesh anchoring reinforcement 9 in the structure disclosed in Fig. 4 of the drawings, I utilize a slate surfaced roll H which bonds or anchors the plastic surface ll thereto due to its granular upper surface.

It will be appreciated that in the modification of my invention as disclosed in Fig. 4 of the drawings I provide a roofing installation comprising a plurality of independent plastic slabs and also provide drainage outlets as in my preferred form. I do not, however, extend the plastic of course G beneath course F. In this form as in my preferred form cracks in the plastic resulting from expansion and contraction are reduced to a minimum.

In Figs. 5 and 6 of the drawings I disclose one example of a method of forming the verges of my roofing installation, The transverse edges of the strips of sheeting 3 are turned down over the edge of the sheathing l and nailed thereto as at 26. It will be clear that the wire mesh will be turned down along with the sheeting. Before the plastic is laid, I mount a removable form 30 in any desirable manner to a roof beam 28. The form 30 being mounted in spaced relation relative to the roof edge to provide a space 30a for the plastic. In order to provide a cut back or stepped construction to the plastic verges, that is to the edge of each plastic panel, I employ wedge members 32 which are disposed against the form 30 on the side thereof adjacent the roof edge. The plastic is poured betwe n the turned down edge of the sheet 3 and eac wedge 32 in the space 30a. This arrangement of the verges of a roof is decorative and attractive in appearance and provides an eificient and durable structure.

In Figs. 7, 8 and 9 of the drawings I show a modified form of roofing installation and method of constructin the same. The same desirable results are obtained by this modified arrangement as in my preferred embodiment, and I shall use the same reference numerals to describe elements similar to those involved in such preferred embodiment.

A roof according to this form of my invention, comprises an exterior plastic shingle simulating water run-off surface designated generally by the numeral I I, which surface is laid on the strips of sheeting 3, which in turn are applied to the wood sheathing I, which in this instance may be treated with an asphalt paint to provide a bond for the plastic. It will be appreciated that the wire mesh or.the slate surfaced roll may be used.

In this modified structure, as in the preferred structure, the plastic material is laid in longitudinal courses E, F, G, etc. and forms or molding bars are employed as previously described. In Figs. 7, 8, 9 let the letter F indicate each fourth course which is to be laid and positioned with respect to the lapped portion 8 with its vertical butt end [3 coplanar with respect to the longitudinal edge of said lapped portion, to provide a water and drainage point.

In this specific example of my invention the workman lays and trowels courses D and E and then places a long straight sheeting supporting board or bar 21 a distance under the end of the lapper portion 8 to thereby dispose such lapped portion user: and spaced from the under lapped portion ll'nfi'tho next adjacent lower strip of sheeting Lift immpcrtanttc note that the supportinglmomher ill ispositioned a distance under the hpped-pcrticnt to provide ran-overhanging portion-l2 which extends. beyond the supporting member. When the lapped portion 8 of the waterproof sheeting has been so supported and position'ed the next course of plastic G is laid and trowelled, the butt end l3 thereof being molded by any desirable type of form or molding bar 29, the supporting member 21 functions as a form for the upper relatively thin end of the course.

Due to the fact that the supporting member 27 defines the upper limit of the course G, it will be clear that the upper end thereof will extend under the overhanging portion l2 of the lapped portion 8, all for a purpose to be hereinafter described and made clear.

Immediately after course G has been laid, course F may then be laid in the following manner. The lapped portion supporting member 21 is removed from under said lapped portion. asphalt mastic 9 having been applied to seal the joint, and the lapped portion 8a is pressed down and sealed to the underlapped portion [0, the overhanging portion l2 resting on the upper thin portion l5 of course G. A form or molding board or the like 3| is next disposed on course G with the upper end thereof disposed against the longitudinal edge of the overhanging portion I2. Plastic is then laid to form the course F, the butt end of course F providing a form for the upper end of course F.

In a roof according to this modified form of invention, it will be seen that I provide a series of drainage points at the longitudinal lower edge of each strip of waterproof sheeting. I accomplish this result by so laying and disposing the plastic courses that the lower longitudinal edge of each strip of sheeting is exposed for drainage of water, which may leak through the plastic, onto the outer surface of the roof.

The roof of Figs. 7, 8 and 9 is of single thickness construction except at the drainage points where the strip overhang and the butt end of course F are laid on and supported by the end I5 of course G. The method by which such roof is laid involves laying the courses as before with the exception that each course which is to be positioned complementary to the lower longitudinal edge of a sheeting strip is not laid until the next adjacent lower course has been laid.

I claim:

1. In the method of forming a roofing installation having an exterior surface composed of a self-hardening plastic material, those steps which comprise laying strips of waterproof sheeting in lapped relation on an under supporting structure, separately laying a series of longitudinal courses of plastic material on each such strip of sheeting so that the butt end of one of such courses is always coplanar with the lower longitudinal edge of each strip of sheeting material, and forming longitudinally extending depressions in the upper surface of each course in the series of courses which is the next adjacent lower course to said course which is disposed with the butt end in coplanar relationship to the longitudinal edge of the strip of sheeting, to provide drainage outlets for water which may leak through the plastic to said strips of waterproof sheeting.

2. In the method of forming a roofing installation having an exterior surface composed of a self-hardening plastic material. those steps which comprisapreparing an under supporting and anchoring structure for the plastic exterior surface, laying a series of longitudinal plastic courses on said supporting and anchoring structure, then laying a second series of plastic courses spaced from said first series of plastic courses, then laying a. longitudinal course of plastic in the area between said two series of plastic courses, the single course of plastic being laid in lapped relation to the next adjacent lower course of said second series of courses.

3. In the method of forming a roofing installation having an exterior surface composed of a self-hardening plastic material, those steps which comprise, laying strips of waterproof sheeting in lapped relation on an under supporting structure, raising and supporting the lower longitudinal edge portions of each strip of sheeting above the under lapped portion of the next adjacent lower strip of sheeting, laying longitudinal courses of plastic material on said sheeting above said raised portion thereof and laying a longitudinal course of plastic below said raised portion of said sheeting with the upper portion thereof extending under a part of said raised sheeting, then lowering said raised portion and laying a cours of plastic on the uncovered area of sheeting between the previously laid courses of plastic.

4. A roofing installation comprising a selfhardening plastic exterior roof surface laid in longitudinal courses and a supporting structure therefor including strips of waterproof sheeting having the longitudinal edge portions thereof lapped to provide a lapped joint between strips of said sheeting, and each longitudinal course of plastic material which is the next adjacent lower course to the lower longitudinal edge of each strip of sheeting having a portion of the upper surface thereof, which is adjacent to the butt edge of the next adjacent course of plastic material, inclined at an angle to the plane of the upper surface of said next adjacent upper course of plastic material, so as to dispose the area of said next adjacent lower course which is adjacent to the lower longitudinal edge of the sheeting below the plane thereof for the unobstructed drainage of water therefrom.

5. A roofing installation comprising a selfhardening plastic exterior roof surface laid in longitudinal courses and a supporting structure therefor including strips of waterproof sheeting having the longitudinal edge portions thereof lapped to provide a lapped joint between strips of said sheeting, and each longitudinal course of plastic material which is the next adjacent lower course to the lower longitudinal edge of each strip of sheeting provided, along the upper longitudinal edge thereof adjacent the butt edge of the next adjacent upper course of plastic material with a longitudinally extending depression in the upper surface thereof to thereby expose the longitudinal edge of the strip of sheeting, for the drainage of water from the sheeting.

6. In the method of forming a roofing installation having an exterior surface composed of a self-hardening plastic material, those steps which comprise laying strips of waterproof sheeting in lapped relation on an under supporting structure, attaching such strips adjacent one edge only to the under supporting structure, separately laying and bonding together a series of longitudinal courses of plastic material on the uppermost strip of sheeting relative to the roof, so that such series of bonded courses of plastic is of. the same dimensions as the strip of sheeting upon which it is laid, separately laying and bonding together a further series of iongitudinal courses of plastic material similar to the first mentioned series of courses, on the next adjacent lower strip of sheeting to that covered with said plastic courses, and forming the upper surface of the uppermost course of said series of courses with a portion extending between the lapped portions of said strips of sheeting, repeating such steps on each next adjacent lower strip of sheeting until all such strips of sheeting are covered with the aforesaid courses of plastic material.

FRANK B. WALLACE. 

